A very deep and involving game. Maybe too much so for the PSP.
Myst's main game genre is point and click adveneture yet it throws in puzzle elements too. Considering that this was made by two brothers several years ago and moving around just means viewing a different slide of the island.
In order to succeed with Myst you need an anylitcal eye, a notepad and pen and the ability to adjust from playing fast paced PSP games to chilling out and enjoying something like Myst.
As a final note, try Myst on whatever format possible as it is a true classic game that everyone should be able to play. The only thing stopping it being totally accessible is the fact that the content of the game needs quite a mature mind and plenty of patience. P.S. it'll be cheap now like £9.99 or $15